Semiconductor device

ABSTRACT

A semiconductor device is provided. The semiconductor device includes a substrate including an active pattern, a gate electrode extending in a first direction and crossing the active pattern which extends in a second direction, a separation structure crossing the active pattern and extending in the first direction, a first gate dielectric pattern disposed on a side surface of the gate electrode, a second gate dielectric pattern disposed on a side surface of the separation structure, and a gate capping pattern covering a top surface of the gate electrode. A level of a top surface of the separation structure is higher than a level of a top surface of the gate capping pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application is a continuation of U.S.application Ser. No. 16/408,912, filed on May 10, 2019, which claimspriority under 35 U.S.C. § 119 to Korean Patent Application No.10-2018-0117040, filed on Oct. 1, 2018, in the Korean IntellectualProperty Office, the entire contents of which are herein incorporated byreference.

TECHNICAL FIELD

The present inventive concept relates to a semiconductor device, andmore particularly, to a semiconductor device including a field effecttransistor.

DISCUSSION OF RELATED ART

Due to their small-size, multifunctionality, and/or low fabricationcost, semiconductor devices have been widely used in the electronicindustry. The semiconductor devices may be classified into a memorydevice for storing data, a logic device for processing data, and ahybrid device including both memory and logic elements. To meet theincreased demand for electronic devices with fast speed and/or low powerconsumption, the semiconductor devices may require high reliability,high performance, and/or multiple functions. To satisfy theserequirements, complexity and/or integration density of the semiconductordevices are being increased.

SUMMARY

Example embodiments of the present inventive concept provide asemiconductor device including a field effect transistor with enhancedelectrical and reliability characteristics.

According to an example embodiment of the present inventive concept, asemiconductor device includes a substrate including an active pattern, agate electrode extending in a first direction and crossing the activepattern which extends in a second direction, a separation structurecrossing the active pattern and extending in the first direction, afirst gate dielectric pattern disposed on a side surface of the gateelectrode, a second gate dielectric pattern disposed on a side surfaceof the separation structure, and a gate capping pattern covering a topsurface of the gate electrode. A level of a top surface of theseparation structure may be higher than a level of a top surface of thegate capping pattern.

According to an example embodiment of the present inventive concept, asemiconductor device includes a substrate including an active patternextending in a first direction, a separation structure crossing theactive pattern and extending in a second direction crossing the firstdirection, a first gate spacer disposed on a side surface of theseparation structure, and a first gate dielectric pattern interposedbetween the separation structure and the first gate spacer. A level of atop surface of the separation structure may be higher than a level of atop surface of the first gate spacer.

According to an example embodiment of the present inventive concept, asemiconductor device includes a substrate including an active pattern,gate electrodes crossing the active pattern, an interlayer insulatinglayer disposed on the gate electrodes, a separation structure extendingvertically from a top surface of the interlayer insulating layer towarda bottom surface of the substrate, the separation structure penetratingan upper portion of the active pattern, and a first gate dielectricpattern disposed on a side surface of the separation structure.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the present inventive concept will be moreclearly understood from the following detailed description taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a plan view illustrating a semiconductor device according toan example embodiment of the present inventive concept;

FIGS. 2A to 2E are cross-sectional views taken along lines A-A′, B-B′,C-C′, D-D′ and E-E′, respectively, of FIG. 1 ;

FIGS. 3, 5, 7, 9, and 11 are plan views illustrating a method offabricating a semiconductor device, according to an example embodimentof the present inventive concept;

FIGS. 4, 6A, 8A, 10A, and 12A are cross-sectional views taken alonglines A-A′ of FIGS. 3, 5, 7, 9, and 11 , respectively;

FIGS. 6B, 8B, 10B, and 12B are cross-sectional views taken along linesB-B′ of FIGS. 5, 7, 9, and 11 , respectively;

FIGS. 6C, 8C, 10C, and 12C are cross-sectional views taken along linesC-C′ of FIGS. 5, 7, 9, and 11 , respectively;

FIG. 12D is a cross-sectional view taken along line D-D′ of FIG. 11 ;

FIG. 12E is a cross-sectional view taken along line E-E′ of FIG. 11 ;

FIGS. 13A and 13B are cross-sectional views, which are taken along linesA-A′ and B-B′, respectively, of FIG. 1 and illustrate a semiconductordevice according to an example embodiment of the present inventiveconcept;

FIGS. 14A and 14B are cross-sectional views, which are taken along linesA-A′ and B-B′, respectively, of FIG. 11 and illustrate a method offabricating a semiconductor device according to an example embodiment ofthe present inventive concept; and

FIGS. 15A and 15B are cross-sectional views, which are taken along linesA-A′ and B-B′, respectively, of FIG. 1 and illustrate a semiconductordevice according to an example embodiment of the present inventiveconcept.

Since the drawings in FIGS. 1-15B are intended for illustrativepurposes, the elements in the drawings are not necessarily drawn toscale. For example, some of the elements may be enlarged or exaggeratedfor clarity purpose. The use of similar or identical reference numbersin the various drawings is intended to indicate the presence of asimilar or identical element or feature.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Example embodiments of the present inventive concept will now bedescribed more fully with reference to the accompanying drawings, inwhich example embodiments are shown.

FIG. 1 is a plan view illustrating a semiconductor device according toan example embodiment of the present inventive concept. FIGS. 2A to 2Eare cross-sectional views taken along lines A-A′, B-B′, C-C′, D-D′ andE-E′, respectively, of FIG. 1 .

Referring to FIGS. 1 and 2A to 2E, a first logic cell LC1 and a secondlogic cell LC2 may be provided and arranged in a second direction D2.Each of the first and second logic cells LC1 and LC2 may constitute alogic circuit (e.g., AND, OR, NAND, NOR, XOR, XNOR, or inverter). Logictransistors constituting the logic circuit may be provided in each ofthe first and second logic cells LC1 and LC2. The logic transistor maybe a fin-type field-effect transistor (FinFET). The first and secondlogic cells LC1 and LC2 may include the same logic circuit or differentlogic circuits. Hereinafter, the structures of the first and secondlogic cells LC1 and LC2 will be described in more detail.

A substrate 100 including a p-type metal-oxide semiconductorfield-effect transistor (PMOSFET) region PR and an n-type metal-oxidesemiconductor field-effect transistor (NMOSFET) region NR may beprovided. The substrate 100 may be a semiconductor substrate (e.g., ofsilicon (Si), germanium (Ge), or silicon-germanium (SiGe)) or a compoundsemiconductor substrate (e.g., of gallium phosphide (GaP), galliumarsenide (GaAs), gallium antimonide (GaSb), indium phosphide (InP),indium arsenide (InAs), indium antimonide (InSb), or indium galliumarsenide (InGaAs)). In an example embodiment of the present inventiveconcept, the substrate 100 may be a silicon wafer.

A second trench TR2 may be provided in an upper portion of the substrate100 to define the PMOSFET region PR and the NMOSFET region NR, and maybe located between the PMOSFET and NMOSFET regions PR and NR. ThePMOSFET region PR and the NMOSFET region NR may be spaced apart fromeach other, in a first direction D1, with the second trench TR2interposed therebetween. Each of the PMOSFET and NMOSFET regions PR andNR may extend in the second direction D2 crossing the first directionD1, and may extend to cross the first and second logic cells LC1 andLC2.

A plurality of active patterns AP1 and AP2 extending in the seconddirection D2 may be provided on the PMOSFET and NMOSFET regions PR andNR. The active patterns AP1 and AP2 may include first active patternsAP1 on the PMOSFET region PR and second active patterns AP2 on theNMOSFET region NR. Each of the first and second active patterns AP1 andAP2, which have a vertically protruding shape, may be a portion of thesubstrate 100. A first trench TR1 may be provided between adjacent onesof the first active patterns AP1 to define the first active patternsAP1, and provided between adjacent ones of the second active patternsAP2 to define the second active patterns AP2. The first trench TR1 maybe shallower than the second trench TR2. For example, a level of abottom of the first trench TR1 may be higher than a level of a bottom ofthe second trench TR2. For example, in comparison to the bottom of thefirst trench TR1, the bottom of the second trench TR2 is closer to abottom surface of the substrate 100.

A device isolation layer ST may be provided to fill the first and secondtrenches TR1 and TR2. Thus, the device isolation layer ST may fill thefirst trench TR1 to define the first and second active patterns AP1 andAP2, and may fill the second trench TR2 to define the PMOSFET region PRand the NMOSFET region NR. The device isolation layer ST may be formedof or include at least one of insulating materials (e.g., silicon oxide(SiO₂)). Each of the upper portions of the first and second activepatterns AP1 and AP2 may have a shape vertically protruding above thedevice isolation layer ST. For example, each of the upper portions ofthe first and second active patterns AP1 and AP2 may have a fin shape.The device isolation layer ST may not cover the upper portions of thefirst and second active patterns AP1 and AP2, and may cover lower sidesurfaces of the first and second active patterns AP1 and AP2.

First source/drain patterns SD1 may be provided on the upper portions ofthe first active patterns AP1, and may be impurity regions of a firstconductivity type (e.g., p-type). A first channel region CH1 may beinterposed between each pair of the first source/drain patterns SD1.Second source/drain patterns SD2 may be provided on the upper portionsof the second active patterns AP2, and may be impurity regions of asecond conductivity type (e.g., n-type). A second channel region CH2 maybe interposed between each pair of the second source/drain patterns SD2.The first channel region CH1 may be the upper portion of each of thefirst active patterns AP1 vertically protruding above the deviceisolation layer ST, and the second channel region CH2 may be the upperportion of each of the second active patterns AP2 vertically protrudingabove the device isolation layer ST.

The first and second source/drain patterns SD1 and SD2 may be epitaxialpatterns that are formed by a selective epitaxial growth process. In anexample embodiment of the present inventive concept, two or moreadjacent first and second source/drain patterns SD1 and SD2 may bemerged with one another in the selective epitaxial growth process. Thefirst and second source/drain patterns SD1 and SD2 may have top surfacesthat are positioned at a level higher than those of the first and secondchannel regions CH1 and CH2. In an example embodiment of the presentinventive concept, the first source/drain patterns SD1 may include asemiconductor material (e.g., SiGe) having a lattice constant greaterthan that of the semiconductor substrate 100. In this case, the firstsource/drain patterns SD1 may exert a compressive stress to the firstchannel regions CH1. In an example embodiment of the present inventiveconcept, the second source/drain patterns SD2 may include the samesemiconductor material (e.g., Si) as that of the substrate 100. Asillustrated in FIG. 2D, the first and second source/drain patterns SD1and SD2 may have a pentagonal or hexagonal shape, but the presentinventive concept is not limited thereto, and the first and secondsource/drain patterns SD1 and SD2 may have various shapes.

Gate electrodes GE may be provided to cross the first and second activepatterns AP1 and AP2 and to extend in the first direction D1, and may bespaced apart from each other in the second direction D2. A pitch betweenadjacent ones of the gate electrodes GE may be a first pitch P1. In thepresent specification, the term “pitch” refers to a distance betweencenters of first and second patterns adjacent to each other.

The gate electrodes GE may vertically overlap the first and secondchannel regions CH1 and CH2. Each of the gate electrodes GE may beprovided to cover a top surface and opposite side surfaces of acorresponding one of the first and second channel regions CH1 and CH2and an upper surface of the device isolation layer ST (e.g., see FIG.2E). In an example embodiment of the present inventive concept, the gateelectrodes GE may be formed of or include at least one of conductivemetal nitrides (e.g., titanium nitride (TiN), tantalum nitride (TaN), ortungsten nitride (WN)) or metallic materials (e.g., titanium (Ti),tantalum (Ta), tungsten (W), copper (Cu), molybdenum (Mo) or aluminum(Al)).

A pair of the gate spacers GS may be respectively provided on theopposite sidewalls of each of the gate electrodes GE. The gate spacersGS may extend along the gate electrodes GE in the first direction D1.Top surfaces of the gate spacers GS may be higher than top surfaces ofthe gate electrodes GE. The top surfaces of the gate spacers GS may becoplanar with a top surface of a first interlayer insulating layer 110,which will be described below. The gate spacers GS may be formed of orinclude at least one of, for example, silicon carbonitride (SiCN),silicon carbon oxynitride (SiCON), or silicon nitride (Si₃N₄). In anexample embodiment of the present inventive concept, the gate spacers GSmay include a multi-layered structure that is made of at least twolayers of silicon carbonitride (SiCN), silicon carbon oxynitride(SiCON), and silicon nitride (Si₃N₄) layers.

Gate dielectric patterns GI may be interposed between the gateelectrodes GE and the first and second active patterns AP1 and AP2. Eachof the gate dielectric patterns GI may extend along a bottom surface ofa corresponding one of the gate electrodes GE, and thus may also beinterposed between the device isolation layer ST and the correspondingone of the gate electrodes GE. Each of the gate dielectric patterns GImay cover the top surface and the opposite side surfaces of acorresponding one of the first and second channel regions CH1 and CH2.The gate dielectric patterns GI may be formed of or include a high-kdielectric material which may have a dielectric constant higher thanthat of the silicon oxide (SiO₂). For example, the high-k dielectricmaterial may be formed of or include at least one of, for example,hafnium oxide (HfO₂), hafnium silicon oxide (HfSiO₄), lanthanum oxide(La₂O₃), zirconium oxide (ZrO₂), zirconium silicon oxide (ZrSiO₄),tantalum oxide (Ta₂O₅), titanium oxide (TiO₂), barium strontium titaniumoxide (BaSrTi₂O₆), barium titanium oxide (BaTiO₃), strontium titaniumoxide (SrTiO₃), yttrium oxide (Y₂O₃), aluminum oxide (Al₂O₃), leadscandium tantalum oxide (Pb(Sc,Ta)O₃), or lead zinc niobate(Pb(Zn_(1/3)Nb_(2/3))O₃).

A gate capping pattern GP may be provided on each of the gate electrodesGE. The gate capping patterns GP may extend along the gate electrodes GEin the first direction D1. The gate capping patterns GP may be formed ofor include at least one of materials, which are selected to have an etchselectivity with respect to first and second interlayer insulatinglayers 110 and 120 to be described below. For example, the gate cappingpatterns GP may be formed of or include at least one of, for example,silicon oxynitride (SiON), silicon carbonitride (SiCN), silicon carbonoxynitride (SiCON), or silicon nitride (Si₃N₄).

The first interlayer insulating layer 110 may be provided on thesubstrate 100. The first interlayer insulating layer 110 may cover thegate spacers GS and the first and second source/drain patterns SD1 andSD2. A top surface of the first interlayer insulating layer 110 may besubstantially coplanar with top surfaces of the gate capping patterns GPand top surfaces of the gate spacers GS. The second interlayerinsulating layer 120 may be provided on the first interlayer insulatinglayer 110 to cover the gate capping patterns GP. In an exampleembodiment of the present inventive concept, the first and secondinterlayer insulating layers 110 and 120 may be formed of or includesilicon oxide (SiO₂). For example, in an example embodiment of thepresent inventive concept, the first interlayer insulating layer 110 andsecond interlayer insulating layer 120 may be implemented as a singleinterlayer insulating layer covering the gate spacers GS, the gatecapping patterns GP and the first and second source/drain patterns SD1and SD2. However, the present inventive concept is not limited thereto.For example, the first and second interlayer insulating layers 110 and120 may be formed of or include different insulating materials.

Active contacts AC may be formed to penetrate the first and secondinterlayer insulating layers 110 and 120 and to be electricallyconnected to the first and second source/drain patterns SD1 and SD2.Thus, the active contacts AC may also be electrically connected to thefirst and second active patterns AP1 and AP2 through the first andsecond source/drain patterns SD1 and SD2. The active contacts AC may besurrounded by the first and second interlayer insulating layers 110 and120 to be insulated from each other and from other conductive elements.The active contacts AC may extend vertically in a third direction D3.The active contacts AC may be formed of or include at least one ofmetallic materials (e.g., aluminum (Al), copper (Cu), tungsten (W),molybdenum (Mo), and cobalt (Co)).

A separation structure SS may be provided on a cell boundary between thefirst and second logic cells LC1 and LC2. The separation structure SSmay extend in the first direction D1 and may separate adjacent ones ofthe first and second logic cells LC1 and LC2 from each other. Theseparation structure SS may extend in the first direction D1 to crossthe PMOSFET and NMOSFET regions PR and NR.

On the PMOSFET region PR, the separation structure SS may extend in thefirst direction D1 and may cross the upper portions of the first activepatterns AP1. The first active pattern AP1 of the first logic cell LC1may be electrically disconnected from the first active pattern AP1 ofthe second logic cell LC2 by the separation structure SS. For example,the separation structure SS may be formed to separate the first activepattern AP1 of the first logic cell LC1 from the first active patternAP1 of the second logic cell LC2. On the NMOSFET region NR, theseparation structure SS may extend in the first direction D1 and maycross the upper portions of the second active patterns AP2. The secondactive pattern AP2 of the first logic cell LC1 may be electricallydisconnected from the second active pattern AP2 of the second logic cellLC2 by the separation structure SS. For example, the separationstructure SS may be formed to separate the second active pattern AP2 ofthe first logic cell LC1 from the second active pattern AP2 of thesecond logic cell LC2.

A hole HO may be formed to penetrate the second interlayer insulatinglayer 120, a gate capping pattern GP, a gate electrode GE and a gatedielectric pattern GI. The hole HO may be positioned between the firstand second logic cells LC1 and LC2. The separation structure SS may fillthe hole HO.

A first recess RS1 may be formed in each of the upper portions of thefirst active patterns AP1 between the first and second logic cells LC1and LC2. The first recess RS1 may also be formed in each of the upperportions of the second active patterns AP2 between the first and secondlogic cells LC1 and LC2. For example, the first recess RS1 may be formedby extending the hole HO into each of the upper portions of the firstactive patterns AP1 between the first and second logic cells LC1 andLC2, or extending the hole HO into each of the upper portions of thesecond active patterns AP2 between the first and second logic cells LC1and LC2. A second recess RS2 may be formed in an upper portion of thedevice isolation layer ST between the first and second logic cells LC1and LC2. For example, the second recess RS1 may be formed by extendingthe hole HO into the upper portion of the device isolation layer STbetween the first and second logic cells LC1 and LC2. The separationstructure SS may fill not only the hole HO but also the first and secondrecesses RS1 and RS2 formed below the hole HO. In other words, theseparation structure SS may extend toward a bottom surface of thesubstrate 100 to penetrate the upper portions of the first and secondactive patterns AP1 and AP2.

The first recess RS1 may be deeper than the second recess RS2. The firstrecess RS1 may be shallower than the first trench TR1. In other words, alevel of a bottom SSb of the separation structure SS penetrating theupper portions of the first and second active patterns AP1 and AP2 maybe higher than a level of a bottom STb of the device isolation layer STfilling the first trench TR1. However, the present inventive concept isnot limited thereto. For example, in an example embodiment of thepresent inventive concept, the first recess RS1 may be deeper than thefirst trench TR1. For example, in an example embodiment of the presentinventive concept, the first recess RS1 may be deeper than the secondtrench TR2.

The separation structure SS may be provided between the gate electrodeGE of the first logic cell LC1 and the gate electrode GE of the secondlogic cell LC2. The gate electrode GE of the first logic cell LC1, theseparation structure SS, and the gate electrode GE of the second logiccell LC2 may be arranged in the second direction D2. Also, the gateelectrode GE of the first logic cell LC1, the separation structure SS,and the gate electrode GE of the second logic cell LC2 may extend inparallel with one another in the first direction D1. A pitch between theseparation structure SS and the gate electrode GE adjacent thereto maybe a second pitch P2. The second pitch P2 may be substantially equal tothe first pitch P1 between adjacent ones of the gate electrodes GE. Forexample, except minor deviation due to process variation, the secondpitch P2 may be equal to the first pitch P1.

A pair of the gate spacers GS may be provided on opposite side surfacesof the separation structure SS. When measured in the second directionD2, a width of the separation structure SS interposed between the pairof the gate spacers GS may be substantially equal to a width of the gateelectrode GE interposed between the pair of the gate spacers GS.

The gate dielectric pattern GI may be interposed between the separationstructure SS and the gate spacer GS. The gate dielectric pattern GI mayhave a vertically extending shape, between the separation structure SSand the gate spacer GS. The gate spacer GS on the separation structureSS may be formed of or include a material the same as that of the gatespacer GS on the gate electrode GE. The gate dielectric pattern GI onthe separation structure SS may be formed of or include a material thesame as that of the gate dielectric pattern GI on the gate electrode GE.

A level of a top surface of the separation structure SS may be higherthan a level of the top surface of the gate capping pattern GP. Also,the level of the top surface of the separation structure SS may behigher than a level of a top surface of the gate spacer GS. The topsurface of the separation structure SS may be substantially coplanarwith the top surface of the second interlayer insulating layer 120 andthe top surface of the active contact AC. The separation structure SSmay be formed of or include at least one of, for example, silicon oxide(SiO₂), silicon nitride (Si₃N₄), or silicon oxynitride (SiON).

A plurality of interconnection layers may be stacked on the secondinterlayer insulating layer 120. The interconnection layers mayconstitute the logic circuits of the first and second logic cells LC1and LC2. The interconnection layers may electrically connect the firstand second logic cells LC1 and LC2 to other logic cells.

FIGS. 3, 5, 7, 9, and 11 are plan views illustrating a method offabricating a semiconductor device, according to an example embodimentof the present inventive concept. FIGS. 4, 6A, 8A, 10A, and 12A arecross-sectional views taken along lines A-A′ of FIGS. 3, 5, 7, 9, and 11, respectively. FIGS. 6B, 8B, 10B, and 12B are cross-sectional viewstaken along lines B-B′ of FIGS. 5, 7, 9, and 11 , respectively. FIGS.6C, 8C, 10C, and 12C are cross-sectional views taken along lines C-C′ ofFIGS. 5, 7, 9, and 11 , respectively. FIG. 12D is a cross-sectional viewtaken along line D-D′ of FIG. 11 . FIG. 12E is a cross-sectional viewtaken along line E-E′ of FIG. 11 .

Referring to FIGS. 3 and 4 , an upper portion of a substrate 100 may bepatterned to form first and second active patterns AP1 and AP2. A firsttrench TR1 may be formed between the first active patterns AP1 andbetween the second active patterns AP2. The first trench TR1 may have ahigh aspect ratio, and thus the width thereof may be narrowerdownwardly. The first trench TR1 may be formed through aphotolithographic process and an anisotropic etching process. A secondtrench TR2 may be formed between a PMOSFET region PR provided with thefirst active patterns AP1 and an NMOSFET region NR provided with thesecond active patterns AP2. The second trench TR2 may be formed througha photolithographic process and an anisotropic etching process.

A device isolation layer ST may be formed on the substrate 100 to fillthe first and second trenches TR1 and TR2. The device isolation layer STmay be formed of or include at least one of insulating materials (e.g.,silicon oxide (SiO₂)). The device isolation layer ST may be formed by achemical vapor deposition (CVD) process, an atomic layer deposition(ALD) process, a physical vapor deposition (PVD) process, or the like.The device isolation layer ST may be recessed until upper portions ofthe first and second active patterns AP1 and AP2 are exposed. Theprocess of recessing the device isolation layer ST may be a wet etchprocess. However, the present inventive concept is not limited thereto.For example, an anisotropic etching process capable of selectivelyetching the device isolation layer ST with respective to the first andsecond active patterns AP1 and AP2 may be performed. As a result, eachof the upper portions of the first and second active patterns AP1 andAP2 may have a shape vertically protruding above the device isolationlayer ST. Accordingly, the first and second active patterns AP1 and AP2may protrude upwardly above the device isolation layer ST by apredetermined height.

Referring to FIGS. 5 and 6A to 6C, sacrificial patterns PP may be formedto cross the first and second active patterns AP1 and AP2. Thesacrificial patterns PP may be line- or bar-shaped patterns extending ina first direction D1. The sacrificial patterns PP may be formed to havea first pitch P1.

The formation of the sacrificial patterns PP may include forming asacrificial layer on the entire top surface of the substrate 100,forming hard mask patterns MA on the sacrificial layer, and patterningthe sacrificial layer using the hard mask patterns MA as an etch mask.The sacrificial layer may be formed by any suitable deposition techniqueknown in the art, including, for example, ALD, CVD, or PVD. Thepatterning of the sacrificial layer may include an anisotropic etchingprocess such as reactive ion etching (RIE) process. In an exampleembodiment of the present inventive concept, the sacrificial layer mayinclude a poly-silicon layer.

A pair of gate spacers GS may be formed on opposite side surfaces ofeach of the sacrificial patterns PP. The gate spacers GS may also beformed on opposite side surfaces of each of the first and second activepatterns AP1 and AP2. For example, the gate spacers GS may be formed tocover exposed portions of the opposite side surfaces of each of thefirst and second active patterns AP1 and AP2 (e.g., not covered by thedevice isolation layer ST and the sacrificial patterns PP).

The formation of the gate spacers GS may include conformally forming agate spacer layer to cover the entire top surface of the substrate 100and anisotropically etching the gate spacer layer. The gate spacer layermay be formed by a CVD process, an ALD process, or the like. The gatespacer layer may be formed of or include at least one of, for example,SiCN, SiCON, or Si₃N₄. In an example embodiment of the present inventiveconcept, the gate spacer layer may have a multi-layered structureincluding at least two layers of SiCN, SiCON, and Si₃N₄ layers.

Referring to FIGS. 7 and 8A to 8C, first source/drain patterns SD1 maybe formed on the exposed upper portion of each of the first activepatterns AP1. A pair of the first source/drain patterns SD1 may beformed at both sides of each of the sacrificial patterns PP.

The upper portions of the first active patterns AP1 may be etched usingthe hard mask patterns MA and the gate spacers GS as an etch mask toform first recess regions. During the etching of the upper portions ofthe first active patterns AP1, the gate spacers GS may be removed fromthe opposite side surfaces of each of the first active patterns AP1, andthe device isolation layer ST between the first active patterns AP1 mayalso be recessed.

The first source/drain patterns SD1 may be formed by a selectiveepitaxial growth process, in which inner surfaces of the first recessregions of the first active patterns AP1 are used as a seed layer. Thefirst source/drain patterns SD1 may have a pentagonal or hexagonalshape, as illustrated in FIG. 8B. However, the present inventive conceptis not limited thereto. For example, the first source/drain patterns SD1may have, for example, a circular shape, an oval shape, or a polygonalshape such as a quadrangular shape. In addition, two or more adjacentfirst source/drain patterns SD1 may be merged with one another in theselective epitaxial growth process. As a result of the formation of thefirst source/drain patterns SD1, a first channel region CH1 may beinterposed between a pair of the first source/drain patterns SD1. In anexample embodiment of the present inventive concept, the selectiveepitaxial growth process may include, for example, a CVD process or amolecular beam epitaxy (MBE) process. The first source/drain patternsSD1 may include a semiconductor material (e.g., SiGe) having a latticeconstant greater than that of the semiconductor substrate 100. Each ofthe first source/drain patterns SD1 may be formed of a plurality ofsemiconductor layers.

In an example embodiment of the present inventive concept, the firstsource/drain patterns SD1 may be doped in situ during the selectiveepitaxial growth process. In an example embodiment of the presentinventive concept, the first source/drain patterns SD1 may be doped withimpurities by an ion implantation process after the formation of thefirst source/drain patterns SD1. The first source/drain patterns SD1 maybe doped to have a first conductivity type (e.g., p-type). For example,the first source/drain patterns SD1 may be formed to includesilicon-germanium (SiGe), and a p-type impurity doping and a heattreatment may be performed so that the first source/drain patterns SD1may serve as a source/drain of a PMOS transistor in the PMOSFET regionPR.

Second source/drain patterns SD2 may be formed on an exposed upperportion of each of the second active patterns AP2. A pair of the secondsource/drain patterns SD2 may be formed at both sides of each of thesacrificial patterns PP.

The upper portions of the second active patterns AP2 may be etched usingthe hard mask patterns MA and the gate spacers GS as an etch mask toform second recess regions. The second source/drain patterns SD2 may beformed by a selective epitaxial growth process, in which inner sidewallsof the second recess regions of the second active patterns AP2 are usedas a seed layer. The second source/drain patterns SD2 may have apolygonal shape, as illustrated in FIG. 8B. However, the presentinventive concept is not limited thereto. In addition, two or moreadjacent second source/drain patterns SD2 may be merged with one anotherin the selective epitaxial growth process. As a result of the formationof the second source/drain patterns SD2, a second channel region CH2 maybe interposed between a pair of the second source/drain patterns SD2. Inan example embodiment of the present inventive concept, the secondsource/drain patterns SD2 may include a semiconductor material (e.g.,Si) the same as that of the substrate 100. The second source/drainpatterns SD2 may be doped to have a second conductivity type (e.g.,n-type). For example, the second source/drain patterns SD2 may be formedto include silicon carbide (SiC) or silicon (Si), and an n-type impuritydoping and a heat treatment may be performed so that the secondsource/drain patterns SD2 may serve as a source/drain of an NMOStransistor in the NMOSFET region NR.

The first source/drain patterns SD1 and the second source/drain patternsSD2 may be sequentially formed by different processes. In other words,the first source/drain patterns SD1 and the second source/drain patternsSD2 may not be formed at the same time.

Referring to FIGS. 9 and 10A to 10C, a first interlayer insulating layer110 may be formed to cover the first and second source/drain patternsSD1 and SD2, the hard mask patterns MA, and the gate spacers GS. In anexample embodiment of the present inventive concept, the firstinterlayer insulating layer 110 may be formed of or include siliconoxide (SiO₂). The first interlayer insulating layer 110 may be formed bya CVD process, a PVD process, a spin coating process, or the like.

The first interlayer insulating layer 110 may be planarized until topsurfaces of the sacrificial patterns PP are exposed. The planarizationof the first interlayer insulating layer 110 may be performed using anetch-back process or a chemical mechanical polishing (CMP) process. Allof the hard mask patterns MA may be removed during the planarizationprocess. Accordingly, the top surface of the first interlayer insulatinglayer 110 may be coplanar with the top surfaces of the sacrificialpatterns PP and the top surfaces of the gate spacers GS.

The sacrificial patterns PP may be replaced with gate electrodes GE. Indetail, the exposed sacrificial patterns PP may be selectively removed.For example, the sacrificial patterns PP may be removed by a wet etchingprocess. However, the present inventive concept is not limited thereto.For example, the sacrificial patterns PP may be removed by a dry etchingprocess. Empty spaces may be formed as a result of the removal of thesacrificial patterns PP. A gate dielectric pattern GI, a gate electrodeGE, and a gate capping pattern GP may be formed in each of the emptyspaces. The gate dielectric pattern GI may be conformally formed so asnot to completely fill the empty space. The gate dielectric pattern GImay be formed by an atomic layer deposition (ALD) or chemical oxidationprocess. In an example embodiment of the present inventive concept, thegate dielectric pattern GI may be formed of or include at least one ofhigh-k dielectric materials.

The formation of the gate electrode GE may include forming a gateelectrode layer to fill the entire remaining portion of the empty spaceand planarizing the gate electrode layer. In an example embodiment ofthe present inventive concept, the gate electrode layer may be formed ofor include at least one of conductive metal nitrides or metallicmaterials. The gate electrode layer may be formed by a CVD process, anALD process, a PVD process, or the like.

Thereafter, an upper portion of the gate electrode GE may be recessed.The gate capping pattern GP may be formed on the recessed gate electrodeGE. The gate capping pattern GP may be formed of or include at least oneof, for example, SiON, SiCN, SiCON, or Si₃N₄. The gate capping patternGP may be formed by a CVD process, an ALD process, a PVD process, or thelike.

Referring to FIGS. 11 and 12A to 12E, a second interlayer insulatinglayer 120 may be formed on the first interlayer insulating layer 110.The second interlayer insulating layer 120 may be formed of or includeat least one of silicon oxide or low-k oxide materials. As an example,the low-k oxide materials may include carbon-doped silicon oxide, suchas SiCOH. The second interlayer insulating layer 120 may be formed by aCVD process.

A hard mask pattern HMP with an opening OP may be formed on the secondinterlayer insulating layer 120. The hard mask pattern HMP may be formedthrough a photolithographic process and an anisotropic etching process.The hard mask pattern HMP may cover a first logic cell LC1 and a secondlogic cell LC2. The opening OP may be formed to expose a cell boundarybetween the first and second logic cells LC1 and LC2. The opening OP mayvertically overlap the gate electrode GE, which is placed on the cellboundary between the first and second logic cells LC1 and LC2.

A hole HO may be formed by an etching process, in which the hard maskpattern HMP is used as an etch mask. The etching process may be ananisotropic etching process. The etching process may be performed tosequentially etch the second interlayer insulating layer 120, the gatecapping pattern GP, the gate electrode GE, and a bottom layer of thegate dielectric pattern GI through the opening OP. The hole HO may beformed to expose the first and second active patterns AP1 and AP2 andthe device isolation layer ST, which are located between the first andsecond logic cells LC1 and LC2. For example, the hole HO may be formedto expose the first and second channel regions CH1 and CH2 and thedevice isolation layer ST, which are located between the first andsecond logic cells LC1 and LC2. The gate dielectric pattern GI coveringthe gate spacer GS may not be etched during the formation of the holeHO. For example, the gate dielectric pattern GI may remain on the gatespacer GS, after the formation of the hole HO. Since the gate dielectricpattern GI may function as a blocking layer in a subsequent etchprocess, by maintaining good film quality of the existing gatedielectric pattern GI during the formation of the hole HO, there is noneed to form a new blocking layer and thus reducing process steps,increasing productivity and enhancing reliability. However, if there isno existing gate dielectric pattern GI, a new blocking layer the same asor similar to the gate dielectric pattern GI may be formed to cover thegate spacer GS in the hole HO.

Referring back to FIGS. 1 and 2A to 2E, the first and second activepatterns AP1 and AP2 exposed by the hole HO may be anisotropicallyetched to form first recesses RS1. The first recess RS1 may be formed topenetrate an upper portion of each of the first and second activepatterns AP1 and AP2. For example, the first recess RS1 may be formed tobe shallower or deeper than the first trench TR1. For example, when thefirst recess RS1 is formed to be deeper than the first trench TR1, itmay be formed to be shallower or deeper than the second trench TR2.

During the selective etching of the first and second active patterns AP1and AP2, the device isolation layer ST exposed by the hole HO may bepartially etched to form a second recess RS2. The second recess RS2 maybe shallower than the first recess RS1.

During the selective etching of the first and second active patterns AP1and AP2, the gate dielectric pattern GI exposed by the hole HO may beused as a blocking layer preventing a lateral etching. The gatedielectric pattern GI may prevent the first and second source/drainpatterns SD1 and SD2 adjacent to the hole HO from being exposed toetchant for the selective etching of the first and second activepatterns AP1 and AP2 (e.g., see FIGS. 2B and 12B). Thus, due to theexistence of the gate dielectric pattern GI covering the gate spacer GSremaining around the hole HO, the first and second source/drain patternsSD1 and SD2 may not be etched during the selective etching of the firstand second active patterns AP1 and AP2. At the same time, the first andsecond active patterns AP1 and AP2 may be successfully etched to cut thefin shape first and second active patterns AP1 and AP2. On the otherhand, without the existence of the gate dielectric pattern GI coveringthe gate spacer GS remaining around the hole HO, the first and secondsource/drain patterns SD1 and SD2 may be attacked by the lateraletching, and at the same time the fin shape first and second activepatterns AP1 and AP2 may not be cut or insufficiently cut.

A separation structure SS may be formed by forming an insulating layerfilling the hole HO, the first recess RS1, and the second recess RS2.The insulating layer may include, for example, a silicon oxide (SiO₂)layer, a silicon nitride (Si₃N₄) layer, or a silicon oxynitride (SiON)layer. The insulating layer may be formed by a CVD process, an ALDprocess, a PVD process, or the like. A planarization process on theinsulating layer may be performed until the second interlayer insulatinglayer 120 is exposed. The planarization of the second interlayerinsulating layer 120 may be performed using an etch-back process or aCHIP process.

Active contacts AC may be formed to penetrate the second interlayerinsulating layer 120 and the first interlayer insulating layer 110 andto be electrically connected to the first and second source/drainpatterns SD1 and SD2. The formation of the active contacts AC mayinclude forming contact holes to expose the first and secondsource/drain patterns SD1 and SD2 and forming a conductive layer to fillthe contact holes. The contact holes may be formed through aphotolithographic process and an anisotropic etching process. Theconductive layer may be formed by a CVD process, an ALD process, a PVDprocess, or the like. Also, a plurality of interconnection layers mayfurther be formed on the second interlayer insulating layer 120. Theinterconnection layers may electrically connect the first and secondlogic cells LC1 and LC2 to other logic cells.

According to an example embodiment of the present inventive concept,during the formation of the separation structure SS, the gate dielectricpattern GI may be used as a blocking layer protecting the first andsecond source/drain patterns SD1 and SD2 adjacent thereto. Thus, aprocess defect may be reduced to enhance reliability of a semiconductordevice.

FIGS. 13A and 13B are cross-sectional views, which are taken along linesA-A′ and B-B′, respectively, of FIG. 1 and illustrate a semiconductordevice according to an example embodiment of the present inventiveconcept. In the following description, an element previously describedwith reference to FIGS. 1 and 2A to 2E may be identified by the samereference number without repeating an overlapping description thereof.

Referring to FIGS. 1, 13A, and 13B, the separation structure SS mayinclude a first portion PA1 and a pair of second portions PA2, which areprovided at both sides of the first portion PA1. The first portion PA1of the separation structure SS may be provided to fill the first recessRS1 and the second recess RS2. The first portion PA1 of the separationstructure SS may extend toward the bottom surface of the substrate 100to penetrate the upper portion of the first or second active pattern AP1or AP2. For example, the first portion PA1 of the separation structureSS may extend vertically in the third direction D3 toward the bottomsurface of the substrate 100 between the first logic cell LC1 and thesecond logic cell LC2 to separate the first and second active patternsAP1 and AP2 of the first logic cell LC1 from the first and second activepatterns AP1 and AP2 of the second logic cell LC2.

The second portion PA2 of the separation structure SS may be provided topenetrate upper portions of the gate spacer GS and the gate dielectricpattern GI. For example, the upper portions of the gate spacer GS andthe gate dielectric pattern GI and portions of the first and secondinterlayer insulating layers 110 and 120 adjacent thereto may bereplaced by the second portion PA2. Thus, the second portion PA2 may beprovided over the gate spacer GS and the gate dielectric pattern GI. Alevel of a top surface of the gate spacer GS below the second portionPA2 may be lower than a level of a top surface of the gate spacer GS onthe gate electrode GE. A level of a top surface of the gate dielectricpattern GI below the second portion PA2 may be lower than a level of atop surface of the gate dielectric pattern GI on the gate electrode GE.In an example embodiment of the present inventive concept, the firstportion PA1 and the pair of second portions PA2 may be formed as oneintegral structure without being separated from each other.

FIGS. 14A and 14B are cross-sectional views, which are taken along linesA-A′ and B-B′, respectively, of FIG. 11 and illustrate a method offabricating a semiconductor device according to an example embodiment ofthe present inventive concept. In the following description, an elementor step previously described with reference to FIGS. 3 to 12E may beidentified by the same reference number without repeating an overlappingdescription thereof.

Referring to FIGS. 11, 14A, and 14B, the hard mask pattern HMP with theopening OP may be formed on the structure of FIGS. 9 and 10A to 10C. Thehard mask pattern HMP may be formed through a photolithographic processand an anisotropic etching process. The hard mask pattern HMP may covermajor portions of the first logic cell LC1 and the second logic cellLC2. The opening OP according to the present embodiment may be formed tobe larger than the opening OP previously described with reference toFIGS. 11 and 12A to 12E. Thus, the opening OP may be formed to overlap acell boundary between the first and second logic cells LC1 and LC2 andportions of the first and second logic cells LC1 and LC2 adjacent to thecell boundary.

The hole HO may be formed by an etching process, in which the hard maskpattern HMP is used as an etch mask. The second interlayer insulatinglayer 120, the first interlayer insulating layer 110, the gate spacerGS, and the gate dielectric pattern GI exposed by the opening OP may beetched during the etching process. A portion of the gate spacer GSexposed by the opening OP may have a top surface that is lower than thatof an unexposed portion of the gate spacer GS. A portion of the gatedielectric pattern GI exposed by the opening OP may have a top surfacethat is lower than that of an unexposed portion of the gate dielectricpattern GI. Although top portion of the gate dielectric pattern may beetched, portions of the gate dielectric pattern GI adjacent to the firstand second source/drain patterns SD1 and SD2 may not be etched andremaining around the hole HO.

Subsequent steps may be performed in the same manner as those describedwith reference to FIGS. 1 and 2A to 2E. According to an exampleembodiment of the present inventive concept, during the formation of theseparation structure SS including the first portion PA1 and the pair ofsecond portions PA2 provided at both sides of the first portion PA1, thegate dielectric pattern GI may be used as a blocking layer protectingthe first and second source/drain patterns SD1 and SD2 adjacent thereto.Thus, a process defect may be reduced to enhance reliability of asemiconductor device.

FIGS. 15A and 15B are cross-sectional views, which are taken along linesA-A′ and B-B′, respectively, of FIG. 1 and illustrate a semiconductordevice according to an example embodiment of the present inventiveconcept. In the following description, an element previously describedwith reference to FIGS. 1 and 2A to 2E may be identified by the samereference number without repeating an overlapping description thereof.

The separation structure SS may be a multi-layered structure including aplurality of insulating layers. As an example, the separation structureSS may include first to third insulating layers IL1, IL2, and IL3. Thefirst to third insulating layers IL1, IL2, and IL3 may extend verticallyto fill the hole HO penetrating the second interlayer insulating layer120 and the gate capping pattern GP. The gate dielectric pattern GIcovering the gate spacer GS may not be etched during the formation ofthe hole HO. For example, the gate dielectric pattern GI may remain onthe gate spacer GS, after the formation of the hole HO.

The first insulating layer IL1 may cover an inner sidewall of the holeHO. The second insulating layer IL2 and the third insulating layer IL3may be provided on the first insulating layer IL1. The second insulatinglayer IL2 may be interposed between the first insulating layer IL1 andthe third insulating layer IL3.

The first to third insulating layers IL1, IL2, and IL3 may be eachindependently formed of or include at least one of, for example, asilicon oxide (SiO₂) layer, a silicon nitride (Si₃N₄) layer, or asilicon oxynitride (SiON) layer. In an example embodiment of the presentinventive concept, the first insulating layer IL1 may be a siliconnitride (Si₃N₄) layer, the second insulating layer IL2 may be a siliconoxide (SiO₂) layer, and the third insulating layer IL3 may be a siliconnitride (Si₃N₄) layer.

In an example embodiment of the present inventive concept, the firstrecess RS1 may be formed during the formation of the first to thirdinsulating layers IL1, IL2, and IL3. In detail, a first anisotropicetching process may be performed to form a first preliminary recess inan upper portion of each of the first and second active patterns AP1 andAP2 exposed by the hole HO. The first insulating layer IL1 may be formedto partially fill the first preliminary recess. A second anisotropicetching process may be performed on the first insulating layer IL1 toform a second preliminary recess, which is deeper than the firstpreliminary recess. The second insulating layer IL2 may be formed topartially fill the second preliminary recess. The first and secondinsulating layers IL1 and IL2 may each be formed by a CVD process, anALD process, or the like. A third anisotropic etching process may beperformed on the second insulating layer IL2 to form the first recessRS1, which is deeper than the second preliminary recess. The thirdinsulating layer IL3 may be formed to completely fill the first recessRS1 provided with the first and second insulating layers IL2 and IL3.The third insulating layer IL3 may be formed by a CVD process, an ALDprocess, a PVD process, or the like.

According to an example embodiment of the present inventive concept, asemiconductor device may include a gate dielectric pattern, which isprovided on a side surface of a separation structure and is used toreduce a process defect. Thus, reliability of the semiconductor devicemay be enhanced.

While example embodiments of the present inventive concept have beenparticularly shown and described, it will be understood by one ofordinary skill in the art that variations in form and detail may be madetherein without departing from the spirit and scope of the appendedclaims.

What is claimed is:
 1. A semiconductor device, comprising: a substrateincluding an active pattern, the active pattern including a plurality ofsource/drain patterns in an upper portion thereof; a gate electrodeextending in a first direction and crossing the active pattern whichextends in a second direction; a pair of first gate spacers on oppositesidewalls of the gate electrode, respectively; a separation structureextending in the first direction through the active pattern, theseparation structure bisecting the active pattern; a pair of second gatespacers on opposite sidewalls of the separation structure, respectively;a first gate dielectric pattern between the gate electrode and the pairof first gate spacers; a first gate capping pattern covering a topsurface of the gate electrode; and a plurality of active contactsconnected to the plurality of source/drain patterns, respectively,wherein the separation structure has a round bottom surface that islower than bottom surfaces of the plurality of source/drain patterns,wherein the separation structure comprises a first insulating layer, asecond insulating layer on the first insulating layer, and a thirdinsulating layer on the second insulating layer, wherein the firstinsulating layer extends from the pair of second gate spacers toward theround bottom surface, and wherein a bottom surface of the secondinsulating layer and a bottom surface of the third insulating layer arein direct contact with the substrate.
 2. The semiconductor device ofclaim 1, further comprising a second gate capping pattern between thepair of second gate spacers, wherein the first insulating layer extendsfrom the second gate capping pattern toward the round bottom surface. 3.The semiconductor device of claim 1, wherein the third insulating layerhas a pillar shape disposed at a center of the separation structure, andwherein the second insulating layer covers opposite sidewalls of thethird insulating layer.
 4. The semiconductor device of claim 1, whereinthe pair of first gate spacers are spaced apart from each other by afirst distance with the gate electrode interposed therebetween, andwherein a width of the separation structure between the pair of secondgate spacers is smaller than the first distance.
 5. The semiconductordevice of claim 1, wherein the plurality of active contacts are arrangedat a first pitch along the second direction, and wherein a width of theseparation structure between the pair of second gate spacers is smallerthan the first pitch.
 6. The semiconductor device of claim 1, furthercomprising a second gate dielectric pattern between the separationstructure and the pair of second gate spacers, wherein the second gatedielectric pattern comprises a high-k dielectric material the same asthat of the first gate dielectric pattern.
 7. The semiconductor deviceof claim 1, wherein the second insulating layer includes an insulatingmaterial different from the first and third insulating layers.
 8. Thesemiconductor device of claim 1, wherein the second insulating layervertically extends between the first insulating layer and the thirdinsulating layer.
 9. The semiconductor device of claim 1, wherein abottom surface of the first insulating layer, the bottom surface of thesecond insulating layer, and the bottom surface of the third insulatinglayer are located at different levels.
 10. The semiconductor device ofclaim 9, wherein a top surface of the first insulating layer, a topsurface of the second insulating layer, and a top surface of the thirdinsulating layer are located at a same level.
 11. The semiconductordevice of claim 1, wherein the plurality of active contacts include afirst active contact and a second active contact that are respectivelyadjacent to both sides of the separation structure, wherein a first oneof the pair of second gate spacers is between the first active contactand the separation structure, and wherein a second one of the pair ofsecond gate spacers is between the second active contact and theseparation structure.
 12. A semiconductor device, comprising: asubstrate including an active pattern, the active pattern including aplurality of source/drain patterns in an upper portion thereof; a gateelectrode extending in a first direction and crossing the active patternwhich extends in a second direction; a pair of first gate spacers onopposite sidewalls of the gate electrode, respectively; a separationstructure in a recess that is formed in the active pattern to bisect theactive pattern and formed between a pair of the plurality ofsource/drain patterns adjacent to each other; a pair of second gatespacers on opposite sidewalls of the separation structure, respectively;a gate dielectric pattern between the gate electrode and the pair offirst gate spacers; a first gate capping pattern covering a top surfaceof the gate electrode; and a plurality of active contacts connected tothe plurality of source/drain patterns, respectively, wherein theseparation structure comprises a first insulating layer, a secondinsulating layer on the first insulating layer, and a third insulatinglayer on the second insulating layer, wherein the first insulating layerextends from the pair of second gate spacers along a sidewall of therecess toward a bottom of the recess, wherein a bottom surface of thefirst insulating layer, a bottom surface of the second insulating layer,and a bottom surface of the third insulating layer are located atdifferent levels, and wherein the bottom surface of the secondinsulating layer and the bottom surface of the third insulating layerare in direct contact with the substrate.
 13. The semiconductor deviceof claim 12, wherein the bottom of the recess is round and lower thanbottom surfaces of the plurality of source/drain patterns.
 14. Thesemiconductor device of claim 12, further comprising a second gatecapping pattern between the pair of second gate spacers, wherein thefirst insulating layer extends from the second gate capping patterntoward the bottom of the recess.
 15. The semiconductor device of claim12, wherein the third insulating layer has a pillar shape disposed at acenter of the separation structure, and wherein the second insulatinglayer covers opposite sidewalls of the third insulating layer.
 16. Thesemiconductor device of claim 12, wherein a top surface of the firstinsulating layer, a top surface of the second insulating layer, and atop surface of the third insulating layer are located at a same level.17. A semiconductor device, comprising: a substrate including an activepattern, the active pattern including a plurality of source/drainpatterns in an upper portion thereof; a gate electrode extending in afirst direction and crossing the active pattern which extends in asecond direction; a pair of first gate spacers on opposite sidewalls ofthe gate electrode, respectively; a separation structure in a recessthat is formed in the active pattern to bisect the active pattern andformed between a pair of the plurality of source/drain patterns adjacentto each other; a pair of second gate spacers on opposite sidewalls ofthe separation structure, respectively; a gate dielectric patternbetween the gate electrode and the pair of first gate spacers; a gatecapping pattern covering a top surface of the gate electrode; and aplurality of active contacts connected to the plurality of source/drainpatterns, respectively, wherein the separation structure comprises afirst insulating layer, a second insulating layer on the firstinsulating layer, and a third insulating layer on the second insulatinglayer, wherein opposite sidewalls of the recess are respectively alignedwith sidewalls of the pair of second spacers that face each other,wherein the first insulating layer extends from a top surface of theseparation structure along the sidewalls of the pair of second spacersand the opposite sidewalls of the recess toward a bottom of the recess,and wherein a bottom surface of the second insulating layer and a bottomsurface of the third insulating layer are in direct contact with thesubstrate.
 18. The semiconductor device of claim 17, wherein the bottomof the recess is round and lower than bottom surfaces of the pluralityof source/drain patterns.
 19. The semiconductor device of claim 17,wherein a bottom surface of the first insulating layer, the bottomsurface of the second insulating layer, and the bottom surface of thethird insulating layer are located at different levels, and wherein atop surface of the first insulating layer, a top surface of the secondinsulating layer, and a top surface of the third insulating layer arelocated at a same level.
 20. The semiconductor device of claim 17,wherein the third insulating layer has a pillar shape disposed at acenter of the separation structure, and wherein the second insulatinglayer covers opposite sidewalls of the third insulating layer.